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Archive for November, 2012

Spectrum Scientifics Microscope Buyer’s Guide – Repost

The holidays have us pretty busy, so here is our Microscope Buyer’s guide for those seeking to buy one!

 

Spectrum Scientifics Microscope Buyers Guide

Congratulations! You’ve decided to buy a microscope! A microscope is a wonderful instrument that can fascinate kids and adults alike. With proper care, a microscope can last a lifetime. But buying a microscope can be confusing for the first time buyer. There are so many different designs, it can be a bit overwhelming. This guide should help you make the proper choice in deciding on a microscope model.

First let’s start by discussing the different designs of microscope. We will break microscopes into three different categories: Compound Microscopes , Inspection/Dissection Microscopes, and ‘Other’. We’ll cover these one by one.

Compound/Biological Microscopes : Compound (or Biological) microscopes are the models designed to be used with slides. They are high powered; using multiple objective lenses (the lenses that point at the slide) to typically provide 40X, 100X, 400X and sometimes 1000X right off the shelf. Modern compound microscopes usually have some sort of illumination from below to light up the slide. Depending on the design of the compound microscope it may have features like binocular eyepieces (two eyepieces, but do not provide stereo vision) a mechanical stage for moving the slide easily, coarse and fine focus (for easy focusing) and different lighting designs.

The disadvantage of a compound microscope is that you pretty much must use it with slides. You can’t just plop a bug, coin, or plant leaf onto the microscope and expect to get a decent image. Compounds aren’t designed to do that. You can cut up the leaf/bug/whatever and make it into a slide with some effort and a slide-making kit, but that does take some time and only lets you view s small part of the the found object.

Inspection/Dissection Microscopes: Inspection/Dissection microscopes are designed to be used with any object you can fit on the microscope’s staging area. This can be coins, stamps, bugs, plant parts, circuit boards, small animals, or whatever else you might find. Inspection Microscopes often have much lower magnification (10x-40x is typical), much wider viewing fields, and very often the binocular versions give true stereo vision. This allows the viewer to ‘work’ (I.e. dissect) on the object being viewed and get a true sense of depth of objects like coins. Inspection Microscopes may have only 1-2 levels of magnification verses the 3-4 on compound microscopes. The microscope will also have top-down lighting, and some may have bottom-up lighting as well. The eyepieces used in many mid-range inspection microscopes are often larger and more comfortable to use.

The disadvantage of a compound microscope is that its magnification is very low and you cannot use it with slides. That means if you want to see cells, bacteria, or other very tiny objects you will need to get a compound microscope as well.

As you can tell from these write-ups, these two designs are very different from each other. Before we discuss the third category, let’s compare and contrast these two designs:

Features: Compound Microscopes vs. Inspection/Dissection Microscopes

Compound Inspection/Dissection
Magnification High: 40x and up Low: 10-40x typical
Levels of Magnification 3, sometimes 4 (40x, 100x 400x typical) 1 or 2*
Lighting From Bottom From top (or top and bottom)
Viewing Monocular or Binocular, but not true stereo Stereo Binocular
Viewable Objects Slides Coins, stamps, bugs, plants, circuit boards, etc.
Extra Features (depends on model) Mechanical Stage, Coarse & Fine Focus, Bottom light
    *Some models of Inspection Microscope have a continuous zoom from 10x to 30 or 40x

This chart should give you some idea of the basic comparison.

We haven’t forgotten about the third category of microscope: Other. This category covers some odd designs that work as specialty instruments. Some examples of Other microscopes would be:

Hand-Held Microscope: These are small, pocket-sized microscopes used in a fashion similar to Inspection/Dissection microscopes. They may have higher magnification than Inspection microscopes (30-100x power), often have a built in light, and are light and portable. Their main disadvantage is they have a limited viewing field- you must put the scope directly on the object being viewed. Their optics & lighting are also rarely up to the quality of full-sized microscopes, and moving to find a specific part of an object can be tricky. Still they are great in the field where a full-size microscope would be unwieldy.

Digital Microscopes: Many traditional microscopes can have a digital camera built into their structure, or can have their eyepiece replaced with a digital camera. But some microscopes are designed from the ground up to be used as high-power digital microscopes. These items have no eyepiece, only a CCD camera and an objective lens. They may have fixed or variable magnification, and the computer screen resolution will vary from model to model. Many ‘toy’-like designs have VGA quality graphics, which is 480 x 640. This level of quality is acceptable for kid’s use but is not sufficiently detail for any real work or study. Usually 1.3 Megapixels is the highest quality available for devoted consumer digital microscopes. If you desire higher resolution a compound microscope with a digital microscope eyepiece might be in order.

High Power Magnifiers: A hand-held magnifier is a very different instrument from a microscope, seeing as how most magnifiers have about 2-3x magnification and microscopes can go as high as 1000x. But some close work magnifiers have very high power (10x and up) and the line between a microscope and a magnifier starts to get blurred. As far as optical design goes, they are still very different animals: The magnifier has just one lens (or set of cemented lenses) while the microscope has both an objective and eyepiece lens. Although the difference is there, the jobs they cover get blurred. If you need a lower powered microscope or a high power magnifier, make certain you are choosing the correct tool for your viewing needs.

Hybrid Microscopes: Given the difference in use between a compound and an inspection microscope it didn’t take to long for some folks to come up with a design that tries to do the job of both microscopes. Usually this is done by taking a compound microscope design and adding a top-down light to the system. These designs can be a great boon to parents or buyers who cannot decide which usage they would prefer. The disadvantage is that like many other things that try to do multiple jobs, they are not the best at either job. Most often hybrid microscopes are better at being a compound microscope than an inspection microscope (mostly due to the higher powers of a compound microscope), but at least the option for using the microscope both ways is available. Consider a hybrid if you can’t decide between designs, but remember it won’t do the job as well as a devoted microscope.

Toy Microscopes: Many ‘toy’ microscopes are available on the market, usually they are either plastic hand-held models or plastic versions of compound designs. The former can be great fun for small children who would like to have something to view nature close-up but can still handle their not-always-delicate hands. The latter, however, is usually to be avoided. Cheap plastic bodies and cheap plastic lenses will give the viewer a very poor experience indeed. Companies that make these items often pile on junk accessories like plastic ‘viewers’, poor slide making accessories, and other gimmicks to cover the fact that the instrument is junk. Avoid these if at all possible.

OTHER THINGS TO CONSIDER

So now that we’ve discussed the various microscope designs, we should talk about that are features of microscopes:

DIN Objectives: DIN stands for Deutsches Institut für Normung – Don’t worry about that. Just understand that DIN eyepieces are set to a higher standard the the average beginner microscope. DIN objectives are generally universal so you can take one DIN objective out of one microscope and thread it into another. DIN eyepieces are often a bit more costly.

Digital Microscope Eyepieces: Digital eyepieces can be a great boon to your viewing experience. When plugged into a computer they can be used to view objects on a much larger screen, and the images can be saved, modified, emailed, etc. Some digital eyepieces can make movies as well. Some microscopes have digital eyepieces built into the body of the microscope, but almost all non-toy microscopes can have their eyepiece’s removed and replaced with a digital microscope eyepiece. The image quality from a digital microscope eyepiece can go from VGA (or even TV) quality all the way up to 5.0 Megapixels or even more.

ACCESSORIES:

One nice feature about microscopes is that they don’t need a whole lot of accessories to get a good experience. But there are a few things you can get to increase your viewing experience:

Prepared Slides: Professionally made slides are always excellent to have around. They let you see objects with a quality that few can match. They also may be of specimens that may be very hard to obtain. Consider having a few prepared slides to enjoy.

Slide Making Kits: Sooner or later you will want to make your own slides. This will involve blank slides, coverslips, a razor (for cutting samples) and some mounting medium. These can be bought individually, but it is often more economical and convenient to buy a kit.

Special Slides: Blank slides with concave dips can be obtained for holding liquid samples. This is excellent for examining microscopic life in pond water and other sources.

Slide Boxes: Once you make your own slides you should store them properly in a slide box. Don’t leave them to get dust and scratches.

Microtome: If you make a lot of slides, cutting thin sample sections with a razor can get annoying after a while. A microtome can help. It is a mechanical device that helps cut a thin sliver off the sample. Think of them as working like the meat slicer at your deli only on a much smaller scale. Microtomes can be hand driven devices for around $75 to fancy automated item costing hundreds or even thousands of dollars.

CONCLUSIONS:

As mentioned above, before you decide on what model microscope you want, make sure you know what it is you want to do with it! Fun can be had viewing both prepared slides and making your own slides using a compound microscope. But it can also be a real thrill to take objects straight from the backyard, or even from your pockets and put them under an Inspection/Dissection microscope. If you have needs beyond having fun observing (research, coin collecting, etc), make certain that your microscope does that sort of job first and foremost.

Happy viewing!

Spectrum Scientifics Telescope Buyer’s Guide Repost

With the holiday’s coming, we’ll have limited time to post on our blog, so to help holiday shoppers we will repost our Telescope Buyer’s Guide.:

 

Spectrum Scientifics Telescope Buyers Guide

There are several telescope buyers guides available on the Internet, some good, some not so good. At Spectrum we are writing from our experience with customers and hope to make this simple and helpful.

Towards that end, the first and in some ways only rule of telescopes is:

Aperture is King!

Aperture is the diameter of the main lens or mirror of the telescope. The bigger it is, the more light the telescope gathers. Do not judge a telescope by its magnification, and stay away from any brand of telescope that sells itself on excess magnification claims (300x!, 600x!, etc.). This is sure sign of poor quality.

More light gathering means better, brighter images, assuming all other things being equal. Decent commercially sold telescopes usually start about 60mm in size (about 2.3”) and go to 20” diameter or more. Roughly speaking, every 2 extra inches of aperture doubles the light gathering capacity of the telescope.

The big problem with getting more aperture is that it increases the size and weight of the telescope. Having a huge, giant telescope with lots of light gathering power has little benefit if it is so heavy you never want to take it out and use it! A minor, but critical caveat to the ‘Aperture is King’ rule is that the small, portable telescope that gets used all the time is more powerful than the giant telescope that never gets moved out of the garage.

What Kind of Telescope?

There are three types of telescope: Reflector, Refractor, and Cassegrain. For beginners purposes, only the first two should be seriously considered. Cassegrain telescope are very nice, but are a bit advanced for first time scope buyers.

Reflector telescopes use parabolic or spherical curved mirrors to gather and concentrate light. The advantage of reflector telescopes is that they are the most economical for larger sizes. The disadvantages are: in inverted image (meaning a reflector telescope cannot be used for looking down the street) and a need for occasional maintenance: the mirror must occasionally be aligned, or collimated to ensure the telescope is working at its best.

 

 

Refractor telescopes use two or more lenses to gather and bend (or refract) light. The advantage for refractors is that, at equal sizes, they provide a more crisp image of the object being view versus a reflector telescope, refractors also can be used for terrestrial viewing (i.e. Looking down the street again), and they do not need to be collimated like reflector telescopes. The disadvantages to refractor telescopes is that as refractor telescopes get larger, they increase in price at a much faster rate than reflectors. At smaller sizes, say 2-3” in diameter, the prices are roughly equal for reflectors and refractors. But by the time you reach a 5” aperture, the price of the refractor will be at least double that of the reflector.

Due to the difficulty of grinding larger lenses, the weight of those lenses, and an optical effect called chromatic aberration (where the light is broken up as it travels through the refractors lens in a manner similar to prisms) refractors generally are not made larger than 5-6” in diameter.

 

 

What Kind of Mount?

Any telescope is going to need a mount! There are three different mount designs to consider: altazimuth, equatorial, and dobsonian. Whatever mount you decide on, it should be strong enough to hold the optical tube without wobbling. Nothing is more annoying than trying to view an object in the sky, only to have it bounce around and be unwatchable because of a poor mount.

Altazimuth Mounts:Altazimuth mounts are simple mounts designed to help aim the telescope in simple up/down (altitude) and left/right (azimuth). Altazimuth mounts are simple and intuitive, and work well for beginners. They are also useful if you wish to use your telescope for terrestrial viewing. The problem with altazimuth mounts is this: objects in the sky do not move in convenient up/down, left/right motion. They move through the sky in an arc (or at least it seems that way to us!). This means that trying to track celestial objects using an altazimuth mount can be like drawing a curve with an etch-a-sketch! For most beginner viewing, this is not an issue, and one can always reacquire an object that moves out of the field of view. But it does mean that if you find a nice object with your telescope, and leave to go let your friends know, it will likely move out of the eyepiece view by the time you come back!

 

 

Equatorial Mounts: Sometimes called German equatorial mounts, are distinguished by their counterweights that are needed to keep the telescope properly balanced. Equatorial mounts require more setup than altazimuth mounts as they must be adjusted to your latitude and aimed North. They are also not as intuitive to aim as altazimuth mounts as they do not follow left/right up/down motions but instead move along declination and right ascension. This follows the path of stars, planets, and deep space objects, but takes some getting used to. The advantages of equatorial mounts are that they can track objects with a turn of a knob, or they can even be motorized. The other advantage is that with some study, the equatorial mount’s setting circles can be used to actually find objects in the night sky! Equatorial mounts are also required for any type of astrophotography, but for beginners this should not be a great concern.

 

 

Dobsonian Mounts: Some consider the Dobsonian to be just variant of the altazimuth mount, and they are not completely wrong. Dobsonians have the same advantages and disadvantages of altazimuth mounts: intuitive movement, no tracking, etc. But the difference is that a Dobsonian mount uses a lazy-susan style platform to move in azimuth and usually some form of hubs to move in altitude. The result is that a Dobsonian mount can handle much, much heavier optical tubes than most altazimuth tripod mounts are capable of handling. Thanks to several improvements in design, Dobsonian mounts have become more and more popular as they are one of the most economical telescope designs on the market today.

 

 

Other Considerations:

The optical tube and mount are major concerns, but they are not the only things one should consider when buying a telescope:

Eyepieces: Eyepieces are often overlooked when buying a telescope, but they should be considered seriously by the beginner as they are 50% of the overall optical system. Almost all telescopes include 2 eyepieces, but by no means are all eyepieces created equal. Cheap telescopes usually include old, cheap eyepiece designs such as Ramsden or Huygenian designs that actually can make the image worse. The telescope you buy should come with eyepieces that, at a minimum, are Kellner or preferably Plossl design. These eyepiece designs are considered the standard for decent eyepieces.

Finder Scope: Every telescope needs a finder scope, a small telescope that sits on top of your main optical tube and aids in aiming the telescope. Most lower end telescopes these days use a reflex finder which projects a red dot onto an optical window to show where the telescope is pointing. These reflex finders are actually easier to use than a cheap finder scope would be. However, for larger telescopes a 6×30 (which stands for: 6 magnification, 30mm aperture) finder scope is much more appropriate. Larger telescopes may also have even larger finder scopes. Avoid telescopes with old 5x finder scopes, or at least be willing to try and attach some sort of reflex finder in its place.

Optional Accessories: Not everything you need for observing the night sky will come with your telescope (and if it does, beware, some companies gussy up cheap scopes with cheap accessories!). There are some things that should be in any astronomer’s ‘kit’. Such as:

  • A Planisphere

Make certain this is one you can read easily at night with your red flashlight!

  • A Red Light Flashlight :

A red flashlight prevents you from losing your night vision the way a regular (white) flashlight would.

  • A Barlow Lens

A Barlow lens is a lens you slip your eyepieces into that then doubles or triples their magnification. Having a barlow is like doubling the number of eyepieces you have. Make sure you have a barlow before you go buying additional eyepieces.

  • A decent Astronomy book

Don’t just buy a book with pretty pictures. Make certain it is a useful book that gives helpful instructions and advice on how to use your telescope, find& observe night-sky objects and other hints. Make certain to read it fully before you go observing, then refer to it during your observation session.

  • Time and good weather

Make certain that you have time for your new hobby. It takes some commitment for even casual viewing. Also, make certain that before you go observing that the weather is decent for viewing. There’s no point in going observing on a night where haze clouds everything in view!

  • Warm clothing

OK, you should really have this stuff already. But it is important to know. Even in warm summer months the temperature can get surprisingly cool at night. Be certain that you are ready for the weather, wherever you are and whenever you observe.

Other accessories you should consider, but are not as crucial as the above items are:

  • FiltersThere are a lot of filters available, and they all help with viewing certain objects. Moon filters cut down on the bright moon (which can actually be painful to view through a large telescope!). Color filters help bring out features of the planets. Sky Pollution filters reduce (but do not eliminate) the effects of light pollution. Read up on their effects and decide if any of these filters are right for your needs.
  • A Carrying Case (for accessories)Eyepieces, barlows, filters, books, & planispheres! All these little parts can be hard to carry and just shoving them into a bag isn’t a very good idea. Consider buying an accessory case to put your eyepieces, etc in for easy transportation. The time to consider getting a carrying case is when moving the accessories is starting to get in the way of your night sky enjoyment.
  • Binoculars!
  • If you haven’t already gotten a full sized pair, you should. Binoculars make for easy viewing, help find night sky objects. And are great for quick viewing. These need not be specifically astronomy binoculars, just a decent pair of full-sized binoculars will work fine. 

Things Not To Worry About

There is plenty to consider when buying your first telescope, but some things should not be worried about. These include:

Astrophotography:

Astrophotography, even in the age of digital cameras, is pretty advanced stuff that requires a lot of time and equipment. Trying to jump into it, or making your telescope buying decisions based on it, is like learning to swim by jumping into a the deep end of the pool. First make certain that you enjoy astronomy, and can commit the time for basic viewing before you even consider taking up astrophotography. Remember that if you need a different mount than what you initially buy as your first telescope that you can usually sell the old telescope at a reasonable price.

Ultra-High End GPS Super GoTo Computer Guidance Systems:

These systems, while great, can actually be problematic. They are expensive, aren’t the ‘idiot-proof’ systems some folks make them out to be, they limit you from learning about the night sky, and many designs actually require that you aim with the computer. This means if the computer’s motors run out of battery power, you can’t even aim the telescope yourself! Basic guidance systems, such as the Orion Intelliscope line are useful for finding objects in the night sky without taking the experience away from you! Consider these instead of completely controlled systems.

Color!

If one were to look through a book of astronomy picture you would think that every view of the night sky through a telescope is awash in bright, pretty colors. Sadly, this is not the case. Most of these photos are taken with long exposure photography and show colors that, while there, are not apparent to the human eye. Be realistic about what you see, and make certain that the telescope you buy doesn’t have tons of unrealistic photos on its box (which were usually taken by the Hubble Space Telescope or the Viking and Voyager probes!).

Above all else BE READY TO ASK QUESTIONS!  Ask your local salesman, ask for advice online. Don’t be shy! Amateur astronomers may be opinionated but they are more than happy to share their experiences and expertise with you!

www.spectrum-scientifics.com

New High Vacuum Pumps from Fischer Technical

For decades Fischer Technical has produced the powerful High-Vacuum 3CFM pump which comes on its own or with a 0-30.00″ Hg Gauge. These are powerful instruments, able to run continuously for long periods of time and capable of producing a near perfect vacuum in most cases.

We’ve carried these units for almost as long as we have been open. A popular set is the Vacuum Experimental Kit which is used by many educational institutions.

These pumps are designed to pump 3 cubic feet per minute (3 CFM) which is pretty good, but could be better. That is why Fischer has recently introduced higher-powered models that can pump much more than their classic model.
So the appearance is the same (Except for the ‘LAV-3″ on the front sticker, but the new units are much more powerful:

Fischer Technical 5 Cubic Feet Per Minute Pump without gauge or with a 0-30″ Hg gauge

Fischer Technical 7 Cubic Feet Per Minute Pump without gauge or with a 0-30″ Hg gauge

Fischer Technical 10 Cubic Feet Per Minute Pump without gauge or with a 0-30″ Hg gauge
These new pumps can fill the need for faster pump down and can handle larger gas loads. All can get as close to vacuum as you could want (better than 28″ Hg ). They can be used for vacuum casting, vacuum ovens,  dessicators, impregnation. They are ideal for a lab’s vacuum needs.

Fischer Technical Vacuums are must more affordable than the competition: Manufacturers like Welch, Cenco  & Leybold. Their comparable models can cost 4-10x as much as the Fischer line.

www.spectrum-scientifics.com

 

 

The Fall Of BuckyBalls

Somewhere in 2008-2009 a few people started realizing that a bunch of spherical  high-powered neodymium magnets were lots of fun to play with. They were an excellent ‘fidget’ toy. They could also be used to make different structures and were overall a lot of fun.

No more.
By the time you read this, BuckyBalls will be a thing of the past. Less than two months ago BuckyBalls announced that they would no longer sell to stores in order to control who buys it. Then, less than two weeks ago, they announced that they would no longer produce BuckyBalls or BuckyCubes. The few sets that remained would be sold online only. In effect, the company was being put out of business.

Why? The CPSC (Consumer Product Safety Commission) initially was satisfied with BuckyBalls efforts to restrict sales to children back in 2010, this year they decided the measures were not enough and demanded that BuckyBalls cease selling them altogether. BuckyBalls  was essentially regulated into oblivion.

The reason for this action was that there had been incidents where children swallowed the magnets. Swallowing one magnet is not a problem, but swallow two or more and they will ‘pinch’ in different parts of the intestine.  There were no deaths but the surgery to resolve this is messy and complicated. There were some 2 dozen incidents out of 2.5 million sets of BuckyBalls sold. In all cases the swallowing was done by children (usually pretending to have tongue or facial piercings) who were not supposed to have the BuckyBalls per the warnings from the company.

There are other companies that produce spherical magnets, but the quality seems to vary from company to company. One set we got as a sample lost its nickel coating very quickly and tarnished. Another lacked the ‘power’ that makes BuckyBalls effective. A further one seemed to use regular magnets with nickel coatings so that it resembled BuckyBalls but was not.

We are saddened by the loss of this product. While it is bad that some kids were injured it should also be noted that BuckyBalls took great pains to keep kids from getting them. It seemed like each week we would get another set of stickers and instructions on who and how to sell BuckyBalls. In all the medical cases the product was being used improperly, and by people who should not have had them.

If you still want some, as of this writing BuckyBalls had a few thousand units remaining that they are selling solely on their own website www.getbuckyballs.com.
www.spectrum-scientifics.com

What’s in the Soil? A classroom soil-testing kit.

We have been adding more classroom items of late, and one of interest is the ‘What’s in the Soil’ kit from American Educational. The kit is large enough for 30 students to run tests.

Using ordinary soil, students perform test such as soil nutrient & mineral analysis (testing for over 10 nutrients & minerals) to determine the effectiveness of plant growth. Students also will determine water content, organic matter content & pH levels. Several soil samples are included in case local soil does not have enough variation.

The kit includes a 9 page teacher’s guide and covers 12 different activities. The kit is designed for students from grades 6-12 9age 11-18).

www.spectrum-scientifics.com

HABA Terra Kids Working Wood Model Kits

We’ve added a small line of products: The HABA Terra kids model kits. These are wood models you punch out the pieces and assemble to make working wood rubber-band powered models.
First up is the Terra Kids Beetle:

 

The Beetle, once assembled, will skitter along with its googly eyes bouncing around and looking silly. Here is  a video tube of the assembly process and the beetle in action:

Next would be the Terra Kids Twirling Prawn Kit:

The Prawn is put together, much like the Beetle, but instead of skittering it twirls around.

Finally, we have the Terra Kids Automobile Kit:

 

This kit is again pieced together from wood punch model pieces. Once assembled the motor will race the car without batteries, just rubber band propulsion! Watch the car getting put together and zoom across the table!

As a company, HABA has been making children’s toys for decades, usually in Europe. These are the first products they have developed that we found were good for our product line. Chek them out!
www.spectrum-scientifics.com

Tectonic Toys

Spectrum Scientifics is proud to carry a very interesting and hard-to-get construction toy: Tectonic Toys

Tectonic Toys are a construction toy designed around shapes. When you get a pack of them, they don’t look like too much, just flat pieces of colorful plastic:

But the secret is that these pieces can be joined together using the Tectonic Hinge, which allows the pieces to be connected to each other. Once together, you can build various colorful multi-sided shapes:

Or more simple shapes like this:

These are just a couple of examples of the shapes that can be made with the pieces. Since there are 324 ways for the Tectonic hinges to connect the possible arrangements is huge. We won’t say infinite, but its pretty darn high!.
Tectonic Toys  are just $20 a set and great for kids or adults who enjoy construction. Each set has 48 pieces – 8 of each color.

www.spectrum-scientifics.com